assume cs:code,ds:data,ss:stack
data segment
		db 'ibm             '
		db 'dec             '
		db 'dos             '
		db 'vax             '
data ends

stack segment
		dw 0,0,0,0,0,0,0,0
stack ends

code segment
	start:
		mov ax,data
		mov ds,ax
		mov bx,0		;bx作为变量，定位每行的起始地址
		mov ax,stack
		mov ss,ax
		mov sp,16
		
		mov cx,4
	s0:
		push cx
		mov si,0
		mov cx,3
	s:
		mov al,[bx+si]
		and al,11011111b
		mov [bx+si],al
		inc si
		loop s
		
		pop cx
		add bx,16
		loop s0
		
code ends
end start